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Battery Chargers

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So, One tool I've been meaning to get for the last 5 years is a battery charger...I know some day its gonna bite me in the behind to not have one, so I figure it might be the perfect Christmas gift...From Dave, To Dave :laugh:

I'd like to get a good one, and from reading reviews this one seems to be the best bang for the buck...what you guys think?
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I guess for the price it should be good. It looks quite capable for up to 6 batteries. You do reallize this is trickle charger? Not sure but it may have more capacity. I myself am a firm believer in trickle storage charging. I have several of these. I just plug them in and forget them until I am ready to use what ever it is plugged into. Generally a 5-7 year battery life is increased to 10-13 years. At least this the kind of preformance I get out of them. I have a seperate charger for the heavy duty charging and starting.

I can find them a little cheaper if I look hard. I even go fancy and made special brackets for the tractors.


You bring up a good point....What KIND of charger should I be looking for then? I'd like it to charge any batteries...some say you need a special charger for AGM/Orbital Batteries/etc... some people use an "old fashioned" charger on anything...
As for battery life, I've always found that a properly maintained/working charging system and quality batteries is all you need. I replaced the battery in my truck last winter after 9 years of use (175,000 miles)...IMO I got my money's worth.
Still have the factory original Delco battery in my 89 Camaro...
I guess for the price it should be good. It looks quite capable for up to 6 batteries. You do reallize this is trickle charger? Not sure but it may have more capacity. I myself am a firm believer in trickle storage charging. I have several of these. I just plug them in and forget them until I am ready to use what ever it is plugged into. Generally a 5-7 year battery life is increased to 10-13 years. At least this the kind of preformance I get out of them. I have a seperate charger for the heavy duty charging and starting.

I can find them a little cheaper if I look hard. I even go fancy and made special brackets for the tractors.
I love the battery tenders...I use them for my motorcycle and Gator in the wintertime. My neighbor had one of the Horrible Freight trickle chargers on his backup generator and within 2 months the battery was cooked bone dry.
Well, I think you need to look at your type of intended use. Oh my, where have I heard that before? :mocking: I guess I just use an old fashioned heavy duty charger for my "back from the dead and jump start" situations. The trickle chargers are really good for extended storage. Like the tractors during the winter, never know when I will need them. And the collector cars during the winter. Otherwise, the tractors don't get put on a charger during the summer, mowing every week.
I wrote a book. This should probably be an article, I have bust it up into two posts.

Let me start out by quoting my Dad:

"There are three things in life that Man will never understand: Economics, Batteries, and Women."

With that as the philosophical groundwork for my comments, here we go:

The vector sum of everything I've read on de-sulfur-ization of batteries is zero. There is some valid chemistry there regarding hi current pulses for removing lead sulfate crystals from the plates. All batteries slowly develop the lead crystals. Their formation both insulates small microscopic sections of the plates and depletes the lead as they sluff off and fall to the bottom of the battery. And there are probably batteries that are just a little bad that can be helped by this process. But my take on this is that if you keep the battery charged enough it's not a problem. The worst thing for a battery is one that is allowed to loose it's charge (through self discharge or user use) and then just sits there, and that's worse if it too hot or too cold. Deep cycle batteries just have different plate construction that has more room between the plates for the crystals and a bigger area in the bottom to catch them.

Electronically detecting if a battery has too much lead sulfate is tricky. As the plates deteriorate, the effective resistance of the battery goes up. The problem is that a small battery, like a motorcycle battery, has a higher effective resistance than a larger tractor battery. And that resistance varies from battery to battery and production run to production run. I built a trickled charger and tester into a device I built (home automation system battery backup). Trying out various gel cells (sealed lead acid battery with the sulfuric acid suspended in a gel), there was no set threshold that worked. I ended up with an algorythm where you "promise" the battery is charged and then I put a small load on it and measure the voltage drop. We're talking small drops in voltage like .050 volts on the small 20 mA load. If that drop triples, the battery is bad. There's more to it than that, but you get the idea. I also have to wait a few days on my charger so the battery can reach it's ultimate at rest voltage. So I don't really understand how some of these units can figure out that a battery is in trouble just by hooking up to it, even if you specify the amp hour rating of the battery.

So with all that said, and mindful of my Dad's disclaimer, I'm not going to worry about lead sulfate. By the time it's a problem, it's time for a new battery.

I got so annoyed at battery things that I build my own charger years ago. It can output up to 5 amps of current, and the output voltage never exceed 13.7 volts. You can short it out (it has foldback current limiting), and you can back feed it (if it's connected to a battery and you unplug it it's OK). Wiring it in reverse pops a fuse which you then have to change. It was great for ham radio rigs that just need 20 amps on transmit.

Now the 13.7 volts is semi magic. Any voltage of 13.8 volts causes electrolysis in a lead acid battery- you start turning the water in the battery into hydrogen and oxygen gas. Now you see a lot of equipment bring a battery up to 14 volts or so when running, and that's OK _if_ the battery needs charging. If it is fully charged, then you start to create the gas (or "boil off" as it is often called). The reason you need the higher voltage is this:

Remember that the battery has an equivalent series resistance? You can think of this as the resistance of all the metal (lead in the plates, steel in the posts) of the pieces that make the battery. Next remember ohms law where:

voltage = current X resistance

Rearrange this and you get:

current = voltage / resistance

Now since that battery has some internal resistance, the only way to pump current into it is to have a voltage difference between the voltage of the battery and the voltage of the charging source. The charger has to be at a higher voltage than the battery. We measure voltage because it's easy (it's an across the terminals, easy to do thing) but current gets the job done. Those little electrons zipping through the lead plates makes the chemical reaction that charges the battery. So in order to charge the battery in some reasonable amount of time, we have to up the voltage so we have some current to charge the battery.

If we run our equipment long enough, the battery is charged and the higher-than-13.8 volt alternator voltage is now starting to "boil off" the battery. So the alternator voltage is a bit of a guess and as long as the battery gets charged we take a bit of abuse when we continue to charge it.

All of the above points out an interesting difference between charging, trickle charging, and maintaining a battery. When we charge a battery, we want to get it up and going in a hurry. So we put lots of voltage on it to get high currents so it charges. If you leave the charger on too long, you can really remove some water through electrolysis. You also loose some water because you are heating up the battery and it can evaporate. The semi-sealed cell caps help prevent this, but it is still happening.

When we trickle a battery, we put a smaller voltage on there that will "top off" the battery, and if the trickle charger is left on for too long there isn't too much damage. We sacrifice speed for tolerance of user error.

When we maintain a battery, in an ideal world, we would never exceed the 13.8 volt limit once the battery was charged. "once the battery was charged" is the problem. When you're pumping current into a battery and remove it, you will see a higher voltage at the time you remove the current than you will after a little time has passed. And all that depends on the size and condition of the battery. Figuring out that a battery is fully charged while you're charging it is a very tricky business. Your cell phone is a closed controlled environment yet the battery indicator is marginal at best. A "works on any battery" charger-maintainer device is a much harder problem.

These three flavors of battery charging devices are implemented differently. The charger can be a cheap transformer with diodes that just blasts current into the device. It can have a switch that selects from different taps on the transformer producing different voltages that make the "2 or 10 amp" charge.

A trickle charger can just be a much smaller transformer with diodes, and it might have a simple regulator (such as a shunt regulator) to make sure it doesn't put too much current in the battery.

The battery maintainer needs to have a regulated clean DC output. The more current it outputs, the more it will cost.

So my home brew charger when put on a battery will output a reasonable amount of current if the battery is at 12V. As the voltage comes closer to the output of the charger (13.7 volts) the current goes down. This is a classic "Walking towards the wall" problem: "You are a distance from the wall, you can take a step that is half of that distance. Do you ever reach the wall? No." So my batteries sit at about 13.65 volts or so. The leakage current on the batter cause that effect. This also gives us yet another 80-20 rule (the 1st one being that in any volunteer organization, 20 percent of the people do 80 percent of the work). 80% of the charging is done in the 1st 20% of the time.

Next post is part 2...
It would be really sweet to have something that can be put on any battery size and it figure out if it's charged and then switches to a float mode and just maintains the battery. IMHO, it seems unlikely that a consumer grade product would have the smarts to do this. So I live with my battery tenders that just have the nice DC output voltage. I use them on my generator battery and the deep cycle battery in the garage that runs the DC emergency lights in the house.

This thread does have me thinking about putting these on my tractors though. It would be pretty simple to whip up a 13.7 volt supply that only outputs a third of an amp or so to keep the battery floated. Next time I do a set of boards I'll do one and see how it works.

I've also read that some people think that keeping a battery tended with a constant voltage causes lead sulfate problems. It might, but I get 4-5 years of standby use on the batteries. I'm sure if they were in normal vehicle use it would be longer.

So getting back to the OP (as everyone collectively moans "FINALLY"), the challenge I see with battery tenders is figuring out how they work. I suspect the Harbor Freight ones where non regulated and they hoped that the low output current would be OK. But remember that "boiling off the water" is a misnomer, you are really seeing electrolysis so even at low currents there will be water loss. A better tender would show 13.8 volts or less open circuit into a volt meter. You'd have to look at the waveform with a scope to see if it was DC or AC with an RMS value. The AC won't work- it will have peak voltages (and currents) that will cause problems.

The polarity protection circuit is a problem too. If you put a diode in series with the charger to protect it, you have the problem that the voltage drop across the diode changes with temperature and current, and that can vary by .2 volts or so. So it can be done, but the device has to sense voltage after the diode which is doable but trickier (more money). My fuse protection is nice (big honking reverse diode and fuse) but it goes against the grain of consumer devices these days which tend to allow any silly mistake with no penalty whatsoever (Hmm. This might explain some of the attitudes we see today). Having to change a fuse is a bother.

Finally, with commercial products, there is the scourge of the Marketing department. A cheap design that just has diodes after a transformer would have pulses of high current, and some marketing idiot could read on the web that high pulses of current can partially reverse lead sulfate deposits and have a bright idea: We take the cheap design, market it as "desulfation", and increase our profit margins. How can the consumer tell if the design tries to figure out things and pules correctly or has a cheap marketing trick?

So, I have a "battery charger" for when I screw up and discharge something. The fact that I did a substantial discharge on a battery means I shorted its life, in the real world there are penalties for errors. I then have my home brew float chargers to maintain batteries. Reading this post and the claims of longer tractor battery life, looks like I need to make a lower power float device and give that a try.

I know this is all clear as mud, but I defer to my fathers observation made some 40 years ago. BTW, I an not capable and refuse to write an article explaining women, bless their hearts.

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Thanks Pete....good read!

I've always viewed (Right or Wrongly) that those battery maintainers are in the same boat as the ShamWow and MightyPutty 2000 :lol:

I was looking for a battery charger for the times as you said "I Screwed up" and left the lights on... Mebbe you can answer this....And this is where I get there a need for a "Special" Charger to charge AGM/Gel Cell, etc... type batteries?
If a "Charger is a charger" Then I'll probably just buy the Associated 9090:
The only difference I'm aware of between a "car battery" and a "gel cell" or better-sealed battery is that when you overcharge a car battery you can just add more water. If you overcharge a gell cell, the hydrogen is stuck in the gel and its performance suffers a bit.

That 9090 model looks like it periodically takes a reading on the battery voltage and decides if the battery is charged OK or not. If left connected it will continue to monitor and blast the battery again if the voltage is too low. So it's better than a "transformer and bridge - good luck" charger but not as good as one that might switch to a floating circuit. On the page in the link, you can see models below that which are advertised as OK for sealed batteries.

I just want to kick someone in marketing for advertising the units further down on the page from the 9090 as "microprocessor controlled". If the 9090 is able to shut off when the battery is charged, then continue to monitor the battery and kick in again, it's highly unlikely that's done with a simple circuit. I use a little microprocessor in a design that has 2 analog inputs and 2 digital outputs and it cost about 60 cents in low volumes. It's really hard make a discrete circuit that would cost less.

So I think the 9090 is an OK "Opps, gotta charge it". In the 2A setting it looks like it will maintain. I'd be nervous using it on a sealed battery. Since the models further down the page state they are OK for gel cell/sealed/AGM it looks like they know the difference.

I gotta tell you, there can't be any good reason for so many models. This is marketing gone mad. Note that on the analyzer units, they tell you the lead wire gauge. But not on the 990 and simpler ones. A stupid game of "the more specs there are, the better it must be." This is also the illusion of choice. If there are all these models and prices, and you carefully think it over and choose, it must be right. In fact, all the manufacturer cares about is you selected on of their products.

So, 9090 OK for standard "car batteries", but if you want sealed or AGM I'd pop up a level to one 9410 or 9420 realizing this was a SWAG analysis. And at the end of the day I'd wonder if I was being played for a fool by the marketing department.

Awesome Pete :thumbup1gif:

I'm just trying to find the sweet spot of "Performance and Price".... for a "just in case I mess up" tool, I hate to spend big bucks for it to sit on the shelf for eons...the 9410 did catch my eye, but at 2x the price (200 bux vs 100) is it worth it. I do want the capability of charging an Exide Orbital in the Wife's car and I plan on going with an Exide Orbital in the Deere when/if that day comes.

I was going down the road of Associated because they are made in the USA and we've always had good luck with them......

I could always buy a JD Charger....the TY26254 (Page 4 on this PDF)
Seems to do it all and recognize the difference in battery types? Price wise its just a little over the 9090
The Deere one "reads" OK- it states that it's good for gel and AGM so that looks good. I'd try to find more data on it on general principal. It's funny how when you surf for chargers, there is now an awareness of the gel cell type batteries that wasn't as widespread a decade ago.

Looking at the size of some units, I'm also going to _guess_ that some battery chargers are roaring kicking and screaming into the 90's by using switching supplies instead of transformers and diodes. The win there is inherent DC output instead of 60 Hz blasts of power. Not sure if the 40 amp unit switches, but the maintainers probably do.

If I hack a maintainer, it will probably take a 24 volt wall wort and switch it down to a current limited back feed-able 13.7 volts.

Found the manual at the Schumacher site:

Wish there was more details, but, it sure looks like you can tell it what kind of battery you have and it handles a lot of different types. The Schumacher site also gives it's chargers a ranking, and this is "Best". Other ranks are "good" and "better". Or as I call it, "crap, might work, and OK".

This looks like a great general purpose charger, you'd still need separate maintainers if you want that functionality. And you can get it in official JD colors too!

Awesome! Glad to have your "blessing" on a charger!
Price wise, The JD one is only 10.00 more then the other one from between that and its easy for me to get this one, I think I will get that JD one.

You know, all kidding aside, I've found the JD Home & Workshop products to be good units at reasonable pricing..... Like my Grill, I LOVE my JD Grill...Made by OMC...Definetly not cheap crap painted green...
This looks like a great general purpose charger, you'd still need separate maintainers if you want that functionality. And you can get it in official JD colors too!

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